Increasing doses of the benzodiazepine, diazepam, or placebo were administered to normal volunteers or drug-free alcoholic inpatients in a single-blind, cross-over study. Following each dose saccadic eye velocity, electroencephalographic power spectra, diazepam blood levels, plasma cortisol, growth hormone and prolactin were measured and self-ratings of anxiety and sedation were performed. After every other dose cognitive testing of memory and attention was performed. The effects of diazepam on these variables was quantified and diazepam dose response curves constructed. These dose response curves provide a measure of benzodiazepine receptor sensitivity in humans.